Silverback Therapeutics to Present Preclinical Data at SITC 34th Annual Meeting Demonstrating SBT6050's Potential for Robust Single Agent Activity in Tumors Refractory to Checkpoint Inhibition

Silverback Therapeutics, Inc., a biopharmaceutical company developing a pipeline of systemically delivered, locally active therapies, will present preclinical data on its lead candidate, SBT6050, at the Society for Immunotherapy of Cancer (SITC) 34^th Annual Meeting taking place November 6-10, 2019 at the Gaylord National Hotel & Convention Center in National Harbor, Maryland.

The presentation, titled "SBT6050, a HER2-Directed TLR8 Agonist Antibody Conjugate, Designed to Overcome Primary Resistance to and Synergize with Checkpoint Inhibition in HER2-Expressing Tumors," shows the potential for ImmunoTACtm SBT6050, a novel therapeutic comprised of a potent TLR8 agonist conjugated to a HER2-directed monoclonal antibody, to drive robust anti-tumor efficacy as a single agent and in combination with checkpoint inhibition. SBT6050 potently activates myeloid cells in a HER2-dependent manner, resulting in the stimulation of multiple anti-tumor immune mechanisms and enabling tumor-localized activity via systemic delivery. In preclinical tumor models refractory to checkpoint inhibition, including T cell deficient xenograft models, an SBT6050 surrogate led to curative single-agent efficacy. Moreover, the single agent efficacy of the SBT6050 surrogate in an immune-competent, checkpoint refractory tumor model was enhanced when combined with an anti-PD1 agent. These preclinical data demonstrate the ability of activated myeloid cells to drive robust anti-tumor efficacy and support clinical evaluation of SBT6050 as a single agent and in combination with checkpoint inhibition in HER2-expressing tumors.

"These data continue to demonstrate the ability of Silverback's technology to localize delivery of potent therapies to specific sites in the body," said Valerie Odegard, Ph.D., Silverback's chief scientific officer. "Our preclinical data highlight SBT6050's ability to activate T cell dependent and independent anti-tumor mechanisms, and its potential to be efficacious as a single agent and in combination, even in settings where immunotherapy has traditionally been ineffective. We look forward to initiating clinical investigation of SBT6050 in 2020."

Presentation details are as follows:

Poster P784: SBT6050, a HER2-directed TLR8 agonist antibody conjugate, designed to overcome primary resistance to and synergize with checkpoint inhibition in HER2-expressing tumors

• Category: Novel Single-Agent Immunotherapies
• Session Date and Time: Saturday, Nov. 9, poster displayed 7:00 a.m. ? 8:30 p.m. EST, poster presented 12:35 ? 2:05 p.m. and 7:00 ? 8:30 p.m. EST.
• Location: Prince George's Exhibition Hall AB

About Silverback's Platform Technology

Silverback's proprietary technology and integrated R&D approach enables the design and development of ImmunoTACtm antibody conjugate product candidates that can be administered systemically, but act only at the sites of disease. This approach is designed to spare healthy tissues from unwanted side effects, while modifying disease processes in a targeted and potent manner. Silverback's platform is useful for developing systemic therapies that can modulate fundamental pathways underlying serious or life-threatening diseases in a targeted manner, in contrast to traditional antibody and small molecule-based approaches that have not been successful due to inadequate activity and/or unacceptable toxicities. Silverback has over 20 patent families directed to the platform and related product candidates.

About Silverback Therapeutics

Silverback Therapeutics is a privately held biopharmaceutical company advancing a pipeline of first-in-class ImmunoTACtm therapies targeting fundamental disease pathways that are systemically delivered but locally active. Enabled by the company's proprietary platform, Silverback's pipeline is rapidly advancing towards clinical studies in several therapeutic areas, including oncology and fibrosis. Since its inception in 2016, Silverback has raised $65 million in venture capital financing from OrbiMed, Celgene Corporation and Alexandria Venture Investments. The company is headquartered in Seattle, Washington. For more information, please visit www.silverbacktx.com.